The present invention relates to a read-write head of an magneto-optical disc player, and more particularly to an improved head capable of quickly searching an area on an optical disc.
There are optical discs such as a CD including a read only CD and a writable CD-R disc which is used as a ROM. Further, as a writable optical disc having a high recording density, a write once disc and a magneto-optical disc are provided. Information is recorded on the disc and reproduced with a laser beam. These discs are different from the CD in the material of the recording surface.
For example, the write once disc has a tellurium or bismuth recording surface on which the lasers burn pits for recording. In another type of the write once disks, the lasers are focused on a recording surface coated with a selenium antimony (Sb.sub.2 Se.sub.3) thin film, or an oxide tellurium (TeOx) thin film, or a thin film of organic pigment, changing the reflectivity of the light.
The magneto-optical disc uses as the recording surface, an amorphous alloy made of rare earth metals such as gallium, terbium, and others. In a magneto-optical recording method, the recording surface of the disc is initially magnetized to form a magnetic field in a direction perpendicular to the surface. The laser heats a predetermined area of the disc to elevate the temperature above Curie temperature, which is about 150.degree. C., thereby reversing the direction of the magnetic field. To read the recorded information, the laser is irradiated on the recording surface so that polarized wave front slightly rotates as a result of the Kerr effect. Thus only the polarized wave deflected by the rotation is read by a photodetector, thereby enabling to read the information.
Referring to FIG. 9, a conventional read-write head for recording information on a magneto-optical disc 1 and reading the information therefrom has a magneto-optical pickup 2 disposed under the disc 1 and a magnetic head 3 disposed above the disc. The pickup 2 and the magnetic head 3 are connected with each other by way of a connecting member 4. The connecting member 4 maintains the relative position between the pickup 2 and the magnetic head 3 constant, so that an area on the disc subjected to a magnetic field of the magnetic head 3 coincides with an area subjected to a laser beam 5 from the pickup 2.
In order to record information on the disc 1, the read-write head is radially moved to an appropriate position of the disc 1. The laser beam 5 from the pickup 2 heats the surface of the disc 1 to Curie temperature. A magnetic field caused by the magnetic head dependent on the information which is to be recorded reverses the direction of the magnetic field on the disc. The information can be written in an area which is already written by modulating the direction of the magnetic field.
Since the magnetic head 3 and the pickup 2 are held together by the connecting member 4, the read-write head is relatively heavy. Hence the head cannot be quickly moved in a radial direction of the disc, which prevents a rapid search of an area on the disc.
Moreover, with the lapse of time, the pickup 2 and the magnetic head 3 may be displaced from each other due to a deformation of the connecting member 4. As a result, the reliability of the optical disc player reduces. In addition, since the connecting member 4 must have a large length in the radial direction of the disc, the player cannot be made much compact.